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Date: Wed, 17 Jan 2024 11:56:26 +0100
From: Daniel Wagner <dwagner@suse.de>
To: Dick Kennedy <dick.kennedy@broadcom.com>
Cc: linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, 
	James Smart <james.smart@broadcom.com>, Hannes Reinecke <hare@suse.de>
Subject: Re: Re: [PATCH] scsi: lpfc: use unsigned type for num_sge
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References: <20231220162658.12392-1-dwagner@suse.de>
 <CAGx+d6cGuC8S2+_ipyKMtOxNQ5a0RW_H46jrwWJjwRx5TRw-ww@mail.gmail.com>
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In-Reply-To: <CAGx+d6cGuC8S2+_ipyKMtOxNQ5a0RW_H46jrwWJjwRx5TRw-ww@mail.gmail.com>

Hi Dick,

On Fri, Dec 22, 2023 at 10:04:50AM -0800, Dick Kennedy wrote:
> The change is good, however, I  don't think this was really the
> problem.

I tried to write the commit message based on the bug report we got. So
yes, it's possible the it is not correct as I was not really involved
and might missinterpret it.

> We would  like to know if this patch really solved an issue they
> observed.

Yes, it fixes the reported problem.

>  A good data point to know is what adapter they're using.

A bunch of different HPE cards which show this log entry: SN1700E,
SN1610E and SN1200E.

>  If that adapter supports hybrid sgl (i.e. phba->cfg_xpsgl), then we
>  would have set the max sg_tablesize = LPFC_MAX_SG_TABLESIZE = 0xffff.
> 
>  But even then, this patch implies that dma_map_sg() returned a crazy
>  huge amount with the MSB set.

Sure, though this seems to be the case.

One noteworthy information is that DIF needs to be enabled to trigger
it:

# cat /sys/module/lpfc/parameters/lpfc_enable_bg
1
# cat /sys/module/lpfc/parameters/lpfc_prot_guard
2

Thanks,
Daniel